JP3674933B2 - Multi-wing radial fan - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multiblade radial fan.
[0002]
[Prior art]
A multiblade radial fan is known that includes an impeller having a number of radially oriented blades spaced apart from each other in the circumferential direction.
The blades of a conventional multi-blade radial fan extend linearly from the inner periphery to the outer periphery of the impeller.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a multiblade radial fan having improved hydrodynamic performance as compared with a conventional multiblade radial fan.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention comprises an impeller having a large number of radially oriented blades spaced apart from each other in the circumferential direction, and the blade rotates the impeller at the outer periphery of the impeller. A multi-blade radial fan characterized by being curved in a direction is provided.
In the present invention, since the blade is curved in the rotational direction of the impeller at the outer peripheral portion of the impeller, the conventional multi-blade radial in which the blade extends linearly from the inner peripheral portion to the outer peripheral portion of the impeller The pressure coefficient increases compared to the fan.
The present invention includes an impeller having a large number of radially oriented blades spaced apart from each other in the circumferential direction, and the blade is curved in the rotational direction of the impeller at the outer peripheral portion and the inner peripheral portion of the impeller. A multi-blade radial fan is provided.
In the present invention, since the blade is curved in the rotational direction of the impeller at the outer peripheral portion of the impeller, the conventional multi-blade radial in which the blade extends linearly from the inner peripheral portion to the outer peripheral portion of the impeller The pressure coefficient increases compared to the fan, and the blades are curved in the direction of rotation of the impeller at the inner periphery of the impeller, so that the blades extend linearly from the inner periphery to the outer periphery of the impeller. Compared with the conventional multi-blade radial fan, the total pressure efficiency is increased.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
A multiblade radial fan according to a first embodiment of the present invention will be described below.
1 to 3, reference numeral 1 denotes a disk-shaped base plate having an outer diameter × plate thickness of 100 mm × 2 mm. Above the base plate 1, an annular top plate 2 having an outer diameter × inner diameter × plate thickness of 100 mm × 58 mm × 2 mm is arranged parallel to the base plate 1 and concentric with the base plate 1. The base plate 1 and the top plate 2 are connected by 120 radial blades having a radial length × height × plate thickness of 21 mm × 20 mm × 0.5 mm arranged at a pitch of 3 ° in the circumferential direction. Has been. A blade-to-blade channel 4 is formed between adjacent blades 3. An impeller 5 is formed by the base plate 1, the top plate 2, and the radial blade 3. The radial blade 3 is curved over the angular range of 22.8 ° with a radius of 6.27 mm in the rotational direction of the impeller 5 indicated by an arrow in FIGS.
[0006]
The impeller 5 is accommodated in a casing 6 having a scroll-shaped flat cross section. The casing 6 has a suction port 6a facing the central opening 5a of the impeller, a discharge port 6b, and a tongue 6c.
A motor 7 is fixed to the outside of the casing 6. The output shaft of the motor 7 extends into the casing 6 and is fixed to the base plate 1.
The operation of the multiblade radial fan according to the present embodiment having the above configuration will be described.
When the motor 7 is started, air is sucked into the casing 6 through the suction port 6 a of the casing 6. The air sucked into the casing 6 flows into the inter-blade channel 4 through the central opening 5 a of the impeller 5. The air that has flowed into the inter-blade channel 4 passes through the inter-blade channel 4 radially outward from the rotating radial vane 3 as indicated by the arrows in FIG. It receives a force in the linear direction, accelerates in the circumferential direction, and is given a centrifugal force.
The air that has passed through the inter-blade channel 5 is ejected radially outward from the outer edge of the inter-blade channel 4, flows in the circumferential direction along the surrounding wall of the casing 6, and flows out of the casing 6 through the discharge port 6b. .
[0008]
The impeller 5 is arranged in a scroll casing 6 having a logarithmic spiral planar shape with a spread angle of 4.5 ° shown in FIG. 4 (the height of the space for accommodating the impeller 5) of 27 mm. did.
As shown in FIG. 5, a suction nozzle is installed on the suction side of a multi-blade radial fan body including an impeller 5, a scroll casing 6 for storing the impeller 5 and a motor 7, and a double chamber is disposed on the discharge side of the fan body. A system air volume measuring device (manufactured by Rika Seiki, model F-401) was installed. The air volume measuring device was provided with an air volume adjusting damper and an auxiliary fan to control the static pressure at the fan outlet. The air flow discharged from the fan was rectified by a rectifying grid. The impeller 5 was rotated at 7000 rpm, the air volume of the fan discharge air was measured with an orifice attached according to the AMCA standard, and the static pressure at the fan outlet was measured with a static pressure hole arranged in the vicinity of the fan outlet.
[0009]
From each measured value of the flow rate of the fan discharge air and the static pressure at the fan outlet, the pressure coefficient ψ was calculated based on the following equation.
ψ = 2 (P _S + P _V ) / (ρV ² )
ψ: Pressure coefficient
P _S : Static pressure [Pa]
P _V = (ρ / 2) V ² : Dynamic pressure [Pa]
ρ: air density [kg / m ³ ]
V = Q / S ₂ : Flow velocity of fan discharge air [m / s]
Q: Flow rate [m ³ / s]
S ₂ : Scroll type casing outlet area [m ² ]
[0010]
FIG. 6 shows the relationship between the fan pressure coefficient ψ obtained by the measurement and the fan flow coefficient φ given by the following equation.
φ = u / v
u = Q / S: Impeller exit radial speed [m / s]
v = rω: Impeller outer peripheral speed [m / s]
S = 2πrh: Impeller exit area [m ² ]
r: Impeller outer radius [m]
h: Height of radial wing [m]
ω: rotational angular velocity [rad / s]
FIG. 6 also shows the relationship between the fan pressure coefficient ψ and the flow coefficient φ when the radial blade 3 extends linearly over the entire length in the radial direction.
From FIG. 6, it can be seen that the pressure coefficient ψ increases by curving the radial blade 3 in the rotation direction of the impeller 5 at the outer peripheral portion of the impeller 5.
[0011]
A multiblade radial fan according to a second embodiment of the present invention will be described below.
As shown in FIG. 7, in the multiblade radial fan according to the present embodiment, the base plate and the top plate of the impeller are 120 pieces of radial length × arranged at a pitch of 3 ° in the circumferential direction. They are connected by a radial blade 13 having a height × plate thickness of 21 mm × 20 mm × 0.3 mm. The radial blade 13 is curved in the rotation direction of the impeller indicated by an arrow in FIG. 7 over the angular range of the radius of 6.27 mm and the central angle of the impeller 5.25 ° at the inner periphery of the impeller. ing. The radial blade 13 extends linearly in the radial direction at the outer periphery of the impeller. Except for the above, the multi-blade radial fan according to the present embodiment has the same configuration as the multi-blade radial fan according to the first embodiment.
[0012]
The impeller of the multiblade radial fan according to the present example was housed in a scroll-type casing shown in FIG. 4, and the hydrodynamic characteristics of the fan were measured using the apparatus shown in FIG.
FIG. 8 shows the relationship between the fan pressure coefficient ψ and the flow coefficient φ when the impeller rotational speed is 5000 rpm, and FIG. 9 shows the relationship between the fan total pressure efficiency η and the flow coefficient φ given by the following equation. Shown in
η = (P _S + P _V ) Q / W
η: total pressure efficiency
P _S : Static pressure [Pa]
P _V = (ρ / 2) V ² : Dynamic pressure [Pa]
ρ: air density [kg / m ³ ]
V = Q / S ₂ : Flow velocity of fan discharge air [m / s]
Q: Flow rate [m ³ / s]
S ₂ : Scroll type casing outlet area [m ² ]
W: Power [W] (= [J / s])
[0013]
FIGS. 8 and 9 show the fan pressure coefficient ψ and flow coefficient φ when the rotational speed of the impeller is 6000 rpm when the radial blade 13 extends linearly over the entire length in the radial direction. And the relationship between the total pressure efficiency η and the flow coefficient φ.
Although the rotational speed of the impeller is different from FIGS. 8 and 9, the fan pressure coefficient ψ is increased by curving the radial blades 13 in the rotational direction of the impeller at the inner periphery of the impeller. It can be seen that the pressure efficiency η tends to increase.
[0014]
The first embodiment and the second embodiment synergize the hydrodynamic performance of the fan by curving the outer peripheral portion and the inner peripheral portion of the radial blade of the multiblade radial fan in the rotational direction of the impeller. It is expected to improve.
[0015]
【The invention's effect】
As described above, in the present invention, since the blades are curved in the rotation direction of the impeller at the outer peripheral portion of the impeller, the blades extend linearly from the inner peripheral portion to the outer peripheral portion of the impeller. The pressure coefficient increases compared to conventional multiblade radial fans.
In the present invention, since the blade is curved in the rotational direction of the impeller at the outer peripheral portion of the impeller, the conventional multi-blade radial in which the blade extends linearly from the inner peripheral portion to the outer peripheral portion of the impeller The pressure coefficient increases compared to the fan, and the blades are curved in the direction of rotation of the impeller at the inner periphery of the impeller, so that the blades extend linearly from the inner periphery to the outer periphery of the impeller. Compared with the conventional multiblade radial fan, the pressure coefficient and the total pressure efficiency are increased.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a multiblade radial fan according to a first embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II in FIG.
FIG. 3 is a partially enlarged sectional view of a blade of an impeller of a multiblade radial fan according to the first embodiment of the present invention.
FIG. 4 is a plan view of a scroll-type casing used for measuring hydrodynamic characteristics of a multiblade radial fan.
FIG. 5 is a diagram showing an outline of an apparatus for measuring hydrodynamic characteristics of a multiblade radial fan.
FIG. 6 is a correlation diagram between a pressure coefficient and a flow coefficient of the multiblade radial fan according to the first embodiment of the present invention.
7 is a partial enlarged cross-sectional view corresponding to FIG. 3 of a blade of a multiblade radial fan according to a second embodiment of the present invention.
FIG. 8 is a correlation diagram between the pressure coefficient and the flow coefficient of the multiblade radial fan according to the second embodiment of the present invention.
FIG. 9 is a correlation diagram between the total pressure efficiency and the flow coefficient of the multiblade radial fan according to the second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base plate 2 Top plate 3 Radial direction blade | wing 4 Flow path between blades 5 Impeller 6 Casing 7 Motor 13 Radial direction blade

Claims (2)

A multi-blade comprising an impeller having a number of radially oriented blades spaced apart from each other in the circumferential direction, wherein the blade is curved in the rotational direction of the impeller at an outer peripheral portion of the impeller Radial fan. It is provided with an impeller having a large number of radially oriented blades spaced apart from each other in the circumferential direction, and the blade is curved in the rotational direction of the impeller at the outer peripheral portion and the inner peripheral portion of the impeller. A featured multi-wing radial fan.

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